C Program to Find the Sum of Fibonacci Numbers at Even Indexes up to N Terms

// C Program to find the sum of
// even-indices Fibonacci numbers
#include <stdio.h>

// Computes value of the first 
// fibonacci numbers and stores
// the even-indexed sum
int calculateEvenSum(int n)
{
    // return 0 if n is equals or less than to 0
    if (n <= 0)
        return 0;

    int fibo[2 * n + 1];
    fibo[0] = 0, fibo[1] = 1;

    // Initialize the result
    int sum = 0;

    // Adding the remaining terms
    for (int i = 2; i <= 2 * n; i++) {
        fibo[i] = fibo[i - 1] + fibo[i - 2];

        // For even indices
        if (i % 2 == 0)
            sum += fibo[i];
    }

    // Return alternating sum
    return sum;
}

// Driver Code
int main()
{

    // Get n
    int n = 5;

    // calculateEvenSum(n) function is computed and return
    // the sum of even-indices Fibonacci numbers.
    int sum = calculateEvenSum(n);

    // display result
    printf("Even indexed Fibonacci Sum upto %d terms = %d",
           n, sum);

    return 0;
}